no / Neuroimmune dysregulation characterizes atopic disease, but its nature and clinical impact remain ill-defined. Induced by stress, the neurotrophin nerve growth factor (NGF) may worsen cutaneous inflammation. We therefore studied the role of NGF in the cutaneous stress response in a mouse model for atopic dermatitis–like allergic dermatitis (AlD). Combining several methods, we found that stress increased cutaneous but not serum or hypothalamic NGF in telogen mice. Microarray analysis showed increased mRNAs of inflammatory and growth factors associated with NGF in the skin. In stress-worsened AlD, NGF-neutralizing antibodies markedly reduced epidermal thickening together with NGF, neurotrophin receptor (tyrosine kinase A and p75 neurotrophin receptor), and transforming growth factor-β expression by keratinocytes but did not alter transepidermal water loss. Moreover, NGF expression by mast cells was reduced; this corresponded to reduced cutaneous tumor necrosis factor-α (TNF-α) mRNA levels but not to changes in mast cell degranulation or in the T helper type 1 (Th1)/Th2 cytokine balance. Also, eosinophils expressed TNF receptor type 2, and we observed reduced eosinophil infiltration after treatment with NGF-neutralizing antibodies. We thus conclude that NGF acts as a local stress mediator in perceived stress and allergy and that increased NGF message contributes to worsening of cutaneous inflammation mainly by enhancing epidermal hyperplasia, pro-allergic cytokine induction, and allergy-characteristic cellular infiltration.

No description available.

O prurido, assim como a dor, é uma experiência sensorial aversiva, associada ao desejo de coçar-se. Resultados prévios deste grupo demonstraram que a injeção i.d. de moléculas doadoras do sulfeto de hidrogênio (H2S), um novo mediador endógeno, reduziu o prurido agudo e a inflamação cutânea induzidos por histamina ou composto 48/80 (C48/80) na pele dorsal de camundongos, sugerindo o envolvimento do H2S no controle do prurido mediado por aminas. Todavia, pouco se conhece sobre os mecanismos envolvidos na indução ou inibição dessa percepção sensorial (aguda ou crônica), e a participação do H2S. A fim de aprofundar esse conhecimento, os objetivos deste estudo foram:i) testar e caracterizar os mecanismos envolvidos nos efeitos protetores de diferentes moléculas doadoras de H2S (liberação rápida e lenta) sobre o prurido agudo e inflamação associada, induzidos por estímulos dependente e independente de histamina, ii) averiguar a capacidade de produção endógena de H2S e as enzimas envolvidas em sua síntese na pele murina saudável e doente, iii) padronizar um modelo de prurido crônico associado ao escore de intensidade da área inflamada na psoríase (PASI), e investigar o efeito protetor de um doador de H2S de liberação lenta (GYY4137). Utilizando camundongos Balb/C, foi realizada a avaliação do comportamento de prurido agudo e inflamação cutânea (extravasamento plasmático, influxo de neutrófilos), frente a diversos estímulos, na ausência e vigência do co- tratamento (i.d.) com doadores de H2S. A psoríase experimental foi induzida pela aplicação tópica do creme imiquimode (IMQ 5%) na pele dorsal destes, por 5 dias consecutivos, e grupos paralelos com a doença foram tratados pela via intraperitoneal (i.p.) com o GYY4137 em diferentes doses (25-100 mg/kg). Os registros do prurido e PASI foram obtidos durante a indução da psoríase e as análises bioquímicas e moleculares foram realizadas ao término do experimento. O tratamento com doses crescentes de GYY4137 (0,3 30 nmol/sitio, i.d.) inibiu o prurido agudo induzido por histamina ou cloroquina e reduziu o influxo de neutrófilos frente ao C48/80, mas não afetou o extravasamento plasmático induzido por histamina ou C48/80. O bloqueio das enzimas geradoras de H2S maximizou o prurido e o influxo de neutrófilos desencadeado por C48/80. O pré-tratamento com a glibenclamida (10 mg/kg; i.p, -30 min), bloqueador dos canais de KATP, não reverteu o efeito do doador de H2S de liberação rápida sobre o prurido agudo e inflamação induzidos por histamina. Em animais com psoríase, o tratamento (i.p.) com o GYY4137 reduziu (P<0,05) a inflamação cutânea (escores PASI) e o prurido, assim como inibiu o eixo NF-<font face = \"symbol\">k B-caspase-1-IL-1<font face = \"symbol\">b , e aumentou a atividade das enzimas antioxidantes (catalase, GST, GR e GPx). A pele de animais com psoríase exibiu menor capacidade na síntese de H2S, que foi paralela à menor expressão da enzima Cistationina-<font face = \"symbol\">b-sintetase (CBS). O bloqueador da enzima Cistationina-<font face = \"symbol\">g-liase (CSE) não interferiu no escore PASI ou prurido. Conclui-se que moléculas doadoras de H2S representam novos alvos terapêuticos no controle da inflamação aguda ou imunomediada associada à percepção de prurido agudo ou crônico. No microambiente inflamatório agudo, o mecanismo envolvido é independente da ativação de canais de KATP, enquanto no crônico (psoríase) é dependente, em parte, da inibição da ativação do eixo NF-<font face = \"symbol\">k B- caspase-1-IL-1<font face = \"symbol\">b e aumento das defesas antioxidantes. / Pruritus, like pain, is an aversive sensory experience associated with the scratching desire. Previous findings from this group demonstrated that hydrogen sulphide (H2S) donor molecules, a new endogenous mediator, when intra-dermal injected, reduced acute histamine and cutaneous inflammation induced by histamine or compound 48/80 (C48/80) on the dorsal skin of mice, suggesting the involvement of H2S in the control of amine-mediated pruritus. However, little is known about the mechanisms involved in the induction or inhibition of this sensorial perception (acute or chronic) and the participation of H2S. In order to get a better understanding, the objectives of this study were: i) to test and characterize the mechanisms involved in the protective effects of different H2S donors molecules (fast and slow release) on acute pruritus and associated inflammation induced by histamine dependent and independent stimuli; ii) to investigate the endogenous production of H2S and the enzymes involved in its synthesis in healthy and unhealthy/disease murine skin; and iii) to standardize a model of chronic pruritus associated with the psoriasis area severity index (PASI) in the inflamed skin, and to investigate the protective effect of a slow release H2S donor (GYY4137). The behaviour evaluation of acute pruritus and cutaneous inflammation (plasma extravasation, neutrophil influx) was performed alongside with different stimuli with or without the co-treatment (i.d.) with H2S donors in Balb/C mice. Experimental psoriasis was induced by topical application of imiquimod cream (IMQ 5%) on the dorsal skin, for 5 consecutive days, and at the same time, groups with the disease were treated intraperitoneally (i.p.) with GYY4137 at different doses (25 100 mg/kg). Records of pruritus and PASI were obtained during psoriasis induction, and biochemical and molecular analyses were performed at the end of the experiment. Firstly, treatment with increasing doses of GYY4137 (0.3 30 nmol/site, i.d.) inhibited acute pruritus induced by histamine or chloroquine and reduced the neutrophils influx induced by C48/80, without affecting histamine or C48/80 plasma-induced extravasation. Secondly, blocking the H2S-generating enzymes potentiated pruritus and the neutrophils influx triggered by C48/80. Pretreatment with glibenclamide (10 mg/kg; i.p., -30 min.), a KATP channel blocker, did not reverse the effect of the fast-release H2S donor on acute pruritus and inflammation induced by histamine. Finally, psoriatic animals, treated with GYY4137 (i.p.) showed a lower skin inflammation (PASI scores) and pruritus as well as the NF<font face = \"symbol\">kB-Caspase1-IL-1<font face = \"symbol\">b axis inhibited (P>0.05), and increased activity of antioxidant enzymes (catalase, GST, GR and GPx). The skin of psoriatic animals exhibited a lower capacity to synthetize H2S, which was parallel to expression of the enzyme Cystathionine-<font face = \"symbol\">b-synthetase (CBS). The Cystathionine-<font face = \"symbol\">g-lyase (CSE) enzyme blocker did not interfere with the PASI or pruritus score. We may conclude that H2S donor molecules represent new therapeutic targets to the control of acute or immune- mediated inflammation associated with the perception of acute or chronic pruritus. Also, in the acute inflammatory microenvironment, the mechanism involved is independent of KATP channels activation, whereas in the chronic condition it is partly dependent on the inhibition of NF-<font face = \"symbol\">kB-caspase-1-IL-1<font face = \"symbol\">b axis activation and increased antioxidants defence.

Die Hämoxygenase 1 (HO-1) ist ein Stressprotein mit antientzündlichen, immunsupprimierenden und zytoprotektiven Eigenschaften, welche in vielen Tiermodellen nachgewiesen wurden. Die zugrunde liegenden Mechanismen sind wenig bekannt. Diese Arbeit demonstriert erstmalig, dass die physiologische Induktion von HO-1 wichtig für die Limitierung von T-Zell-abhängigen Hautentzündungen ist. So führt der HO-1-Inhibitor, Zinn-Protoporphyrin IX (Sn-PPIX), zu einer verstärkten Hautentzündung im Mausmodell. Die pharmakologische Induktion von HO-1 durch Kobalt-Protoporphyrin IX, Co-PPIX, hemmt dagegen die Entzündung in DNFB- bzw. TMA-induzierten murinen Kontaktallergiemodellen sowohl bei Verabreichung von Co-PPIX während der Sensibilisierung als auch vor der Auslösung. Bemerkenswerterweise hemmt eine Co-PPIX-Behandlung die Antigen-induzierte T-Zellproliferation ex vivo in Milzzellen von behandelten Mäusen und in vitro in humanen mononukleären Zellen des peripheren Blutes. Da eine HO-1-Induktion durch Co-PPIX nur in Monozyten und in aus Monozyten abgeleiteten myloischen Dendritischen Zellen (MDDC), nicht aber in T-Zellen, beobachtet wurde, fokussierten alle weiteren Untersuchungen auf Antigen-präsentierende Zellen. HO-1-Induktion durch Co-PPIX reduziert die Expression von MHC-Klasse II und akzessorischen Molekülen und steigert die Phagozytose und den oxidativen Burst von Monozyten. Die immunphänotypische Differenzierung und Maturierung von MDDC wird gehemmt. Funktionsteste zeigen eine Reduktion der Expression und Sekretion von proinflammatorischen und immunstimulatorischen Zytokinen, während die Sekretion des antientzündlichen Zytokins IL-10 gesteigert ist. Die Fähigkeit der MDDC zur Antigenpräsentation gegenüber T-Helferzellen ist für Allo- und Recallantigene stark herabgesetzt. Mittels adenoviraler HO-1-Transduktion von MDDC konnte die Spezifität der Effekte bestätigt werden. Diese Daten zeigen, dass eine verstärkte HO-1-Aktivität die Dendritischen Zellen zu einem unreifen und immunkompromittierten Phänotyp verändert und weisen darauf hin, dass die HO-1-Induktion einen wichtigen Ansatz für die Hemmung der zellulären Immunität und für die Behandlung von T-Zell-abhängigen Hautentzündungen darstellt. / Heme oxygenase 1 (HO-1) is an antiinflammatory stress protein. Its immunosuppressive and cytoprotective activities have been demonstrated in several animal models. The underlying mechanisms, however, are poorly understood. This study demonstrates for the first time that the physiological induction of HO-1 is important for the limitation and resolution of T cell-dependent skin inflammation. So, the HO-1 inhibitor, tin protoporphyrin IX (Sn-PPIX), augments cutaneous inflammation in mouse model. Moreover, pharmacologic HO-1 induction by the potent HO-1 inducer, cobaltic protoporphyrin IX (Co-PPIX), inhibits inflammation when applied around sensitization or before challenge in murine DNFB- and TMA-induced contact hypersensitivity models. Remarkably, Co-PPIX treatment inhibits antigen-driven T cell proliferation both ex vivo in murine splenocytes and in vitro in human peripheral blood mononuclear cells. Since induction of HO-1 mRNA and protein was found in monocytes and monocyte-derived myeloid dendritic cells (MDDC) but not T cells, further investigations focused on antigen-presenting cells. HO-1 induction by Co-PPIX depresses monocytic MHC class II and accessory molecule expression whereas phagocytosis and respiratory burst activities are augmented. Moreover, HO-1 induction inhibits the immunophenotypic differentiation and maturation of MDDC. Functional analysis revealed a decreased proinflammatory cytokine production whereas secretion of the antiinflammatory cytokine IL-10 is increased. Remarkably, the antigen-presenting capacity of MDDC for T-helper cells is diminished both for allo- and for recall-antigens. Adenoviral HO-1 transduction of MDDC confirmed that the effects are mediated by HO-1. These data indicate that an enhanced HO-1 activity switches myeloid DCs to an immature and functionally compromised phenotype and suggest that HO-1 induction represents an important approach for depressing T cell immunity and for the treatment of T cell-dependent skin inflammation.